Cancer is a global health challenge, with a rapidly rising incidence and a significant economic burden. The urgent need for innovative approaches to cancer prevention and treatment is underscored by its growing impact. Marine algae, characterized by their unique bioactive compounds, have emerged as promising sources of novel anticancer agents in this context. This chapter reviews the potential of marine algae in cancer prevention and treatment, emphasizing the integration of traditional knowledge with modern scientific methods to develop safe, affordable, and accessible anticancer drugs. Marine algae offer a rich source of bioactive compounds, including polysaccharides, polyphenols, and pigments, known for their antioxidant, anti-inflammatory, and antitumor effects. Moreover, these organisms have evolved complex defense mechanisms, making them particularly interesting for drug discovery. Research highlights the multifaceted anticancer mechanisms of marine algae, including apoptosis induction, cell cycle arrest, and selective cytotoxicity against cancer cells. Fucoxanthin, fucoidan, stigmasterol, and other compounds from marine algae have shown potent anticancer properties through modulation of various signaling pathways. The advantages of marine algae include their chemical diversity, sustainability, and environmentally friendly cultivation, presenting exciting opportunities for anticancer drug development. To address the challenges of traditional herbal medicine, standardization, active compound identification, and rigorous clinical trials are essential. Collaboration between traditional practitioners and scientists can bridge the gap between traditional wisdom and modern medical standards. Combinatorial therapies that integrate herbal extracts with conventional treatments offer the potential for more effective and holistic cancer management.